(1) Field of the Invention
This invention relates to novel spirobibenzofuran compounds and more particularly, to novel 3,3'(2H,2'H)-spirobibenzofuran compounds useful as an antioxidant and also to antioxidants comprising the same.
(2) Description of the Prior Art
It is well known that dyes, dyestuffs or polymer materials deteriorate by an oxidation reaction with oxygen from the air. A variety of deterioration inhibitors have been developed to prevent such deterioration. Various types of antioxidants are known including, for example, derivatives of hydroxybenzenes such as phenol, hydroquinone and the like, and piperidine derivatives, and the like.
Hydroxybenzenes are described, for example, in U.S. Pat. Nos. 2,735,765, 3,700,,455, 3,764,337, 3,770,431, 3,930,866, 4,138,259 and 4,388,404. Piperidine derivatives are described, for example, in U.S. Pat. Nos. 4,452,884, 4,465,757, 4,465,765 and 4,584,265 and British Pat. No. 1,326,889.
However, these known deterioration inhibitors unsatisfactory for use as a deterioration inhibitor for a color photographic dye or dye image. Accordingly, there is a demand for antioxidants which can improve the stability of the photographic image.
Also, the known deterioration inhibitors did not show any satisfactory effect when used as an antioxidant for natural or synthetic polymers and, thus, there is a demand for powerful antioxidants for this purpose.